Here is a look at some of the stories that CNN plans to follow this week:

Polls show tight GOP races in Michigan, Arizona

A recent surge in support for GOP presidential candidate Rick Santorum gets important tests this week in Michigan and Arizona, both of which hold primaries on Tuesday, one week before the Super Tuesday contests in 10 states.

A poll taken late last week showed that the overall front-runner for the GOP presidential nomination, Mitt Romney, was leading Santorum 39% to 35% among likely primary voters in Arizona. In Michigan, recent polls show Romney and Santorum neck-and-neck.

Also this week, Wyoming will announce the results of its 20-day caucus process on Wednesday. And Washington state's caucuses are scheduled for Saturday.

Santorum has led Romney in national polling in recent days, thanks in part to strong primary and caucus performances in Colorado, Minnesota and Missouri earlier this month. But by Sunday, Santorum's lead was down to 1 percentage point in one poll, with Romney closing the gap after a debate in Arizona on Wednesday.

Romney still has a significant lead in the delegate count on the strength of results in early primaries and caucuses, including the winner-takes-all primary in Florida.

Fed chairman to give "state of the economy"

The economy is a key issue in the presidential campaign, and Wednesday will be a big day for economic reports.

Federal Reserve Chairman Ben Bernanke will give the House Financial Services Committee his latest assessment of the U.S. economy. His testimony coincides with the release of the Fed's economic summary, the Beige Book, which is issued eight times a year.

Also Wednesday, the Bureau of Economic Analysis will release its revised estimate of fourth-quarter real gross domestic product. Real GDP is the output of goods and services produced by labor and property located in the United States. In addition, the Bureau of Labor Statistics will issue 2011 annual unemployment averages, broken down by state and region.

On Thursday, the Commerce Department will issue its reports on January construction spending and personal income and outlays.

Leap Day

Wednesday is February 29, a date that occurs just once every four years. For most of us, it's just another day, inserted to keep the calendar balanced. But for a select club of special people, it's a quadrennial holiday of major proportions. It's their birthday.

Are you or someone you love a leapling? Tell us what it means to you and how you celebrate it.

Vladimir Putin, Russia's once and future president?

Vladimir Putin is seeking a return to Russia's presidency in next weekend's nationwide elections.

Russians head to the polls next Sunday. Putin, who was president from 2000 to 2008, wants to reclaim the office he left because of a law barring him from serving more than two consecutive terms. He became prime minister as Dmitry Medvedev took over as president, and Medvedev is not running for another term.

Russia's third-richest man, billionaire New Jersey Nets owner Mikhail Prokhorov, is one of the people running against Putin.

The election will come about three months after parliamentary elections that kept Putin's ruling United Russia party in power, albeit with a smaller majority. The results caused mass protests in Russia, with protesters claiming that the results were rigged in United Russia's favor. At the time, Medvedev proposed sweeping political reforms - including suggestions that Russia return to direct elections of regional governors; simplify the registration of political parties and presidential candidates; and establish a new editorially independent national public TV channel.

U.N. Human Rights Council to discuss Syria

The United Nations' Human Rights Council is expected to meet early this week in Geneva to discuss the Syrian government's nearly yearlong violent crackdown on opposition. The meeting comes as the International Committee of the Red Cross tries to negotiate a temporary cease-fire in Homs, Syria, one of the flashpoints in an uprising against Syrian President Bashar al-Assad.

The ICRC has urged combatants to stop fighting for two hours each day so they can deliver humanitarian aid to Homs and other cities. In Homs, government forces have shelled an opposition stronghold neighborhood for more than three weeks, destroying homes and forcing residents to hide in makeshift shelters, where food, medical and other supplies are running low, a CNN team observed more than a week ago.

Al-Assad has denied reports that his forces are targeting civilians, saying they are fighting armed gangs and foreign fighters bent on destabilizing the government. But many accounts inside the country say Syrian forces are killing civilians as part of a crackdown on anti-government opposition.

This week's human rights meeting comes after Sunday's referendum in Syria on changes to the country's constitution, in what the government touts as a move toward reform.

Mush! Iditarod sled race to begin

The 40th Iditarod Trail Sled Dog Race begins with a ceremonial start Saturday in Anchorage, Alaska. Racing in earnest begins the next day in the town of Willow. The route covers 975 miles, ending in Nome; there are 24 checkpoints along this year's northern route.

Sixty-six mushers are registered to run the race with teams averaging 15 dogs each; that means about 1,000 dogs will be running, barking and scooping up mouthfuls of snow. The dogs will have microchips and tracking collars, and 52 veterinarians will be dispersed along the trail to watch over their health.

A purse of $550,000 will be divided among the first 30 finishers. The fastest anyone has finished the race is 8 days, 22 hours, 46 minutes, 2 seconds, accomplished by Martin Buser in 2002. The slowest winning time was recorded by Carl Huntington in the race's second year, 1974: 20 days, 15 hours, 2 minutes, 7 seconds.

The race is not considered to be over until the last musher arrives in Nome. The dubious record for slowest finishing time belongs to John Schultz, who in the first Iditarod, in 1973, finally completed the 1,150-mile course in 32 days, 15 hours, 9 minutes and 1 second. The last finisher is awarded a red lantern to symbolize being the caboose on the train of mushers.